Cut to the Bone

Madagascar was once home to giant lemurs, giant tortoises, and the world’s largest avian species: flightless elephant birds, Aepyornis maximus, that weighed over a thousand pounds. These megafauna disappeared from the island between 2,500 and 500 years ago. One theory suggests that humans caused the extinction, given evidence that our predecessors arrived on Madagascar roughly 4,000 years ago—shortly before the decline of these large animals began. However, a new study of markings found on elephant bird bones suggests that people set foot on the island much earlier than previously thought, casting doubt on the theory that early settlers were the culprits behind Madagascar’s megafauna extinction.

Zoologist James Hansford at the Zoological Society of London, UK, found the bone markings while researching the diversity and distribution of elephant birds. To determine when and if human tools made the markings, he and a team of scientists investigated bones collected from museums and research centers in Europe, the United States, and Madagascar. They examined the patterns and orientation of the markings under multiple levels of magnification and characterized them using established protocols for determining human butchery on bone. Radiocarbon dates were obtained from two separate laboratories to reduce the possibility of dating errors.

From their analyses, the researchers concluded that the markings were consistent with cuts and bevels caused by human-made, sharp-edged tools in the course of hunting or butchering. Furthermore, the markings were dated to over 10,000 years ago, suggesting that humans were on Madagascar 6,000 years earlier than was previously known.

Hansford says the results prompt “a paradigm shift” in thinking regarding the relationship between the arrival of humans and the extinction of Madagascar’s large-bodied animals. Rather than an immediate cause of their decline, humans coexisted with elephant birds and other megafauna for almost 9,000 years, the results suggest. The nature of this coexistence, along with where these humans came from, and why they have gone undetected in the early Holocene fossil record until now, is yet unknown. The results “raise more questions than they answer,” says Hansford. (Science Advances)